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Where Does Wastewater Go?

San Francisco’s Sewer Collection System


Every time you flush the toilet, take a shower, brush your teeth, do your laundry, or wash the dishes; this wastewater is collected and treated by the City's sewer system.

Pollution Prevention - debris, oil in catch basins

Protecting our environment is a partnership, and we all need to do our part. Our various Pollution Prevention programs are designed to make it easy for everyone to do the right thing: prevent pollution at the source.

Our sewer system collects and treats sewage from homes and businesses, stormwater (rainwater) and street runoff into the drains. This is our City’s lifeline protecting public health and environmental quality. Nearly one million residents, businesses and visitors rely on our sewer system every day.


We own and operate about 1,900 miles of sewer mains and laterals right under the street. End to end, it would stretch from here to Colorado (and back) and over 300 miles are more than 100 years old! In the last few years, we have increased the routine replacement of the sewers from 4 to 15 miles per year.

To ensure that San Francisco continues to have a reliable and seismically safe sewer system, we are moving forward with the Sewer System Improvement Program (SSIP).

Did You Know ButtonFootball stadium

How much wastewater is treated every day?

Each non-rainy day more than 80 million gallons of wastewater is collected and transported to one of three treatment plants (Southeast, Oceanside, and NorthPoint), where harmful pollutants like human waste, oil and other pesticides are removed before reaching the San Francisco Bay and Pacific Ocean. (When it rains, our wastewater system collects and treats up to 500 million gallons a day).

In just six days, you could fill a football stadium from top to bottom with wastewater. Our system is hard at work everyday! 


Learn how San Francisco is unique. Next: Our Combined Sewers.

Last updated: 7/26/2018 2:44:27 PM